| Title | Modelling the Flow Paths at the Carbfix2 Reinjection Site, Hellisheiði Geothermal Power Plant, SW-Iceland |
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| Authors | Thomas RATOUIS, Sandra Ósk SNÆBJÖRNSDÓTTIR, Bergur SIGFUSSON, Ingvi GUNNARSSON, Gunnar GUNNARSSON, Edda Sif ARADÓTTIR |
| Year | 2020 |
| Conference | World Geothermal Congress |
| Keywords | geothermal, reservoir modelling, TOUGH2, Multiple Interacting Continua (MINC), Sustainability, Carbon Capture and Storage, CCs |
| Abstract | The CarbFix2 project was developed to dispose of CO2 and H2S emissions from the Hellisheiði Power Plant, SW Iceland by mineralization of the injected gases within the subsurface basalts. The gas mixture is dissolved and transported to an injection well where it is co-injected with separated water from the power station. The injection of CO2 and H2S takes place in the Húsmúli reinjection area and has been an integral part of the operations at the Hellisheiði Geothermal Power Plant since 2014. Field scale three-dimensional models of the injection at Húsmúli are developed to characterize and constrain the flow paths between the CarbFix reinjection site and the nearby Skardsmýrarfjall production zone. Mineralization processes occur along the flowpath between these areas and the models will be used to assess the impact of the CarbFix injection on the production wells. The numerical model is centered on the area between the reinjection and production zone. The model is based on the geological and structural model of Húsmúli developed using a multidisciplinary approach combining geological data, induced seismicity and tracer tests conducted in 2013 and 2014. The model results suggest a strong anisotropy control at Húsmúli likely to be associated with extensional faults acting as preferential pathways for the fluid. The model shows a good match to the tracer recovery match from the observation wells and shows limited adverse impact in term of enthalpy decline of the production fluid at Skardsmýrarfjall during the simulation time. The model also suggests that the flow path between the injection and production zones are lengthened due to the density difference of the colder injected fluid which sinks before rising as it heats up. This has a direct impact on surface area of rock that the fluid comes into contact with and the storage potential of the CarbFix reservoir. |